Anime can sometimes have a terrible reputation for unnecessary sexualisation of people who are rather too young. For example, the recent The Ryou's Work is Never Done, of which I could only watch a single episode. And I had similar misgivings about this show, which was briefly described as being about Satou, a teenage girl, and her deep and abiding love for Shio, a tiny child.
And the first episode does run for a fair while with that premise, but you shouldn't let that put you off. There's an important distinction here. Even though Satou tends to obsess worryingly about the appealing nature of a child, the show doesn't. It's all too aware that this is not normal, and doesn't attempt to pretend it is.
Because even though there's vague hints of affection here, the real point of the anime is horror. See, Satou is a yandere. If anyone tries to stop her cheerful life with Shio, she might just do horrible things to them. With a crowbar. And good lord are a lot of people trying to interfere or steal Shio for their own purposes. We've got paedophile teachers, traumatised teenagers, sexually harassing managers and bitchy girls.
You do have to wonder somewhat where everybody's family is. Shio doesn't have much of a memory, but does have hints of something horrible, as well as someone trying to hunt her down. Satou is maintaining a double life to keep them fed, and is pretending to stay with an aunt. But my god do all of these people need a responsible adult. And probably some therapy.
Don't be put off by the first ten minutes. It's very uncomfortable, but it knows it, and is doing it intentionally. There's a lot of psychological horror going on here, with Satou and Shio each having their own little mental breaks, with some neat animation twists to drive the moment home. We've not had some really good horror for a while, but this is definitely it.
[UPDATE]: Having watched a little further, I am officially re-titling this Everyone Is Insane, No Seriously, I Mean Literally Everyone: The Anime.